An electric motor control system includes a master control module, a drive module, and a monitoring module. The master control module is configured to output a low-voltage drive signal to the drive module, the drive module converts the low-voltage drive signal into a high-voltage drive signal and outputs the high-voltage drive signal to a power unit, and the power unit outputs, according to the high-voltage drive signal, a power supply drive signal provided by a high-voltage battery. The monitoring module is electrically connected with the master control module and the drive module, and is configured to acquire the low-voltage drive signal, and output a fault signal to the master control module when the low-voltage drive signal is abnormal, to control the master control module to stop outputting the low-voltage drive signal.

A method for starting and protecting an induction motor is disclosed. The method includes starting the induction motor, detecting an initialization fault associated with the induction motor, monitoring operation of the induction motor, detecting an operation fault while monitoring operation of the induction motor, and stopping the induction motor if the initialization fault or the operation fault is detected.

Power distribution modules in distributed antenna systems include fan monitoring circuits for indicating an alarm condition to head-end equipment. The alarm condition can be used by system operator/owners that a fan is drawing excessive power, thereby detracting from system performance, or indicating that the fan may fail. The alarm condition signal can be returned to the head-end equipment via an uplink communication path between a remote unit powered by the module and the head-end equipment.

Power distribution modules in distributed antenna systems include fan monitoring circuits for indicating an alarm condition to head-end equipment. The alarm condition can be used by system operator/owners that a fan is drawing excessive power, thereby detracting from system performance, or indicating that the fan may fail. The alarm condition signal can be returned to the head-end equipment via an uplink communication path between a remote unit powered by the module and the head-end equipment.

Provided is a brake apparatus, a brake control method, and a method for determining a lock abnormality in a motor capable of reducing motor drive noise at the time of a self-diagnosis of the motor regardless of a condition. A brake control method includes issuing a drive instruction to repeat ON/OFF driving a plurality of times and drive a motor in such a manner that a rotational frequency of the motor during an OFF time period does not fall to zero and a peak of the rotational frequency of the motor during an ON time period increases as the ON/OFF driving is repeated, carrying out terminal voltage detection to detect a terminal voltage of the motor at the time of the ON/OFF driving carried out by the issuing of the drive instruction, and determining a lock abnormality in the motor to determine whether there is the lock abnormality in the motor based on a characteristic of the terminal voltage during the OFF time period of the ON/OFF driving that is detected by the carrying out of the terminal voltage detection.

Provided is a brake apparatus, a brake control method, and a method for determining a lock abnormality in a motor capable of reducing motor drive noise at the time of a self-diagnosis of the motor regardless of a condition. A brake control method includes issuing a drive instruction to repeat ON/OFF driving a plurality of times and drive a motor in such a manner that a rotational frequency of the motor during an OFF time period does not fall to zero and a peak of the rotational frequency of the motor during an ON time period increases as the ON/OFF driving is repeated, carrying out terminal voltage detection to detect a terminal voltage of the motor at the time of the ON/OFF driving carried out by the issuing of the drive instruction, and determining a lock abnormality in the motor to determine whether there is the lock abnormality in the motor based on a characteristic of the terminal voltage during the OFF time period of the ON/OFF driving that is detected by the carrying out of the terminal voltage detection.

A protective redundancy circuit is provided for a power tool having an electric motor. The protective redundant subsystem is comprised of: a motor switch coupled in series with the motor; a motor control module that controls the switching operation of the motor switch; and a protective control module that monitors switching operation of the motor switch and disables the power tool when the switching operation of the motor switch fails. In the context of an AC powered tool, the switching operation of the motor switch is correlated to and synchronized to the waveform of the AC input signal. During each cycle or half cycle, the motor control module introduces a delay period before closing the motor switch and the protective control module determines the operational status of the motor switch by measuring the voltage across the motor switch during the delay period.

A power conversion apparatus includes a main circuit unit, a control unit, a current sensor, and a half-wave rectifier unit. The control unit includes current frequency calculation units and monitoring units. The current frequency calculation units calculate current frequencies based on at least either the rising timing or falling timing of current detection signals half-wave rectified by the half-wave rectifier unit. The monitoring units monitor the speed of a motor based on the current frequencies calculated by the current frequency calculation units.

An electronically commutated motor driving module for driving a motor includes a voltage detector, an electronically commutated motor driver, a current detector, a voltage converter, and a controller. The voltage detector detects supply voltage to generate a voltage detection signal. The electronically commutated motor driver is supplied by the supply voltage to generate, according to an electronically commutated signal, an operating current for driving the motor. The current detector detects the operating current to generate a current detection signal. The voltage converter converts the supply voltage into an internal voltage. The controller is supplied by the internal voltage and generates the electronically commutated signal according to a plurality of control parameters. When the controller determines that a specific event has happened according to the control parameters, the controller stops generating the electronically commutated signal and then stores the control parameters.

A power conversion apparatus includes a main circuit unit, a control unit, a current sensor, and a half-wave rectifier unit. The control unit includes current frequency calculation units and monitoring units. The current frequency calculation units calculate current frequencies based on at least either the rising timing or falling timing of current detection signals half-wave rectified by the half-wave rectifier unit. The monitoring units monitor the speed of a motor based on the current frequencies calculated by the current frequency calculation units.